Advanced Theories

Benjamin Wallace-Wells, in writing about A. Garrett Lisi, notes that I said, “I am now convinced his theory doesn’t work” (“Surfing the Universe,” July 21st). I think space-time has important quantum structure and is even crystalline, as Newton and Fresnel thought. But Lisi’s is not so much a physical theory as matériel for constructing one, and it is inappropriate to judge it at this early stage. The next step in theory construction, called quantization, is to turn on quantum indeterminacy. What I really reacted against, and the criticism applies to most current theories, is that the usual quantization method keeps the space-time continuum. But other methods convert the standard space-time continuum to something more atomistic, like a cosmic diamond film or a buckyball, and then Lisi’s beloved E(8) might describe its unit cell. Einstein famously went through theories that didn’t work on his way to one that did, and so do his successors. Fixing a theory that doesn’t work is part of the job.